Method for constructing a plastic lined concrete structure and structure built thereby

ABSTRACT

A method for constructing a plastic lined concrete tank includes the forming of a plurality of plastic lined concrete panels. Each of the panels is made up of a concrete slab and a plastic sheet. The concrete slabs have opposed, laterally spaced, elongated edges and an inner surface and the plastic sheet each have a plurality of anchoring projections protruding outwardly from a face thereof. The panels are formed in such a way that the face of each plastic sheet is engaged against the surface of a corresponding concrete slab with the anchoring projections embedded in the concrete of said corresponding slab. The plastic sheets are arranged, configured and positioned such that a respective edge flap portion thereof projects outwardly beyond each edge of the corresponding slab and each such edge flap portion has an outboard segment. The panels are preferably constructed flat on the ground and then erected into a standing position and arranged in adjacent, aligned positions around a periphery of a tank foundation with the inner surfaces of the slabs facing inwardly, with the elongated edges of the slabs extending upwardly, with the respective elongated edges of each slab disposed in opposing spaced relationship relative to the elongated edges of adjacent slabs to thereby present elongated gaps therebetween, with the plastic sheets disposed within the tank periphery, and with the outboard segments of the edge flap portions of each sheet overlapping the outboard segments of the edge flap portions of the sheets of adjacent panels at said gap. The overlapping outboard segments are then welded together.

CROSS REFERENCE TO RELATED APPLICATION

None

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to the field of concretestructures of the sort which may often be used in the construction ofopen topped or domed, ground level or elevated tanks and the like thatmay generally be used to hold liquids, for example, water. In particularthe present invention relates to plastic lined concrete structures andthe methodology used in the fabrication of composite plastic linedconcrete structures where the plastic lining is securely affixed to aconcrete wall. The invention has special utility in connection withplastic lined prestressed/post-tensioned concrete tanks.

2. The Prior Art Background

Concrete tanks have been widely used for decades to hold fresh or wastewater, and the like. Generally speaking such tanks are highlycommercially valuable properties, and a large construction industry hasbeen established to serve the needs of a variety of activities andenterprises which desire an economical and reliable means for holding areadily available supply of fresh water or for storing waste waterduring and/or prior to treatment. Such tanks are currently available insizes ranging from about 50,000 gallons to several million gallons ormore.

Prior art concrete tanks, while extremely successful in many regards,have had limited applicability in situations where the liquid to becontained is capable of reacting with or otherwise harming concrete.

To increase the overall applicability of concrete tanks, plastic liningshave been proposed to limit the exposure of the interior walls of tanksto the material contained therein. However, it has been a very difficultand expensive operation to attach large sheets of plastic to concretewalls in such a way that the plastic sheets are securely attached to thewalls and all of the seams between adjacent sheets have completeintegrity.

SUMMARY OF THE INVENTION

The present invention provides a solution for many of the problemsencountered previously in the construction of plastic lined concretetanks. That is to say, in accordance with the concepts and principles ofthe invention, a method is provided for efficiently and economicallyconstructing plastic lined concrete structures wherein the structuralintegrity of the incorporated plastic linings is greatly enhanced. Inthis latter regard, the methodology provided by the invention isparticularly applicable to all varieties of concrete tanks, including,for example, and without limitation, concrete tanks that are standardcast-in place, wire wound and prestressed, and internally tendoned andpost-tensioned. Thus, in one form of the invention, the same provides amethod that includes forming first and second plastic lined concretepanels, each panel including a concrete slab having an elongated edgeand a surface, and a plastic sheet having a plurality of anchoringprojections protruding outwardly from a face thereof. The forming of thepanels is conducted in such a way that the face of each plastic sheet isengaged against the surface of a corresponding concrete slab and theanchoring projections are embedded in the concrete of the correspondingslab. In addition, the plastic sheets are each arranged and positionedsuch that an edge flap portion thereof projects outwardly beyond theedge of the corresponding slab. The formed panels are arranged inadjacent, aligned positions with the elongated edge of the concrete slabof the first panel disposed in opposing spaced relationship relative tothe elongated edge of the concrete slab of the second panel so that anelongated gap is presented between the edges. In addition, an outboardsegment of the edge flap portion of the plastic sheet of the first panelis disposed in overlapping relationship relative to an outboard segmentof the edge flap portion of the plastic sheet of the second panel atsaid gap. The overlapping segments are then welded together with anupwardly extending seam.

In another adaptation of the invention, a method is provided forconstructing a plastic lined concrete structure which comprisesproviding first and second plastic sheets, each sheet having a face anda plurality of anchoring projections protruding outwardly from the face.In this adaptation, the method further includes forming a first plasticlined concrete panel by causing a first quantity of wet cementitiousmaterial to come into contact with a portion of the face of the firstplastic sheet, permitting the first quantity of cementitious material toset in the form of a first solid concrete slab having the anchoringprojections of the first plastic sheet embedded therein. The firstconcrete slab desirably has an elongated edge and the first plasticsheet and the first quantity of wet cementitious material are initiallyarranged relative to one another such that an edge flap portion of thefirst plastic sheet projects outwardly beyond the edge of the first slabafter the cementitious material has become set. Also in this adaptationof the invention, a second plastic lined concrete panel is formed inessentially the same manner as the first plastic lined panel. The formedpanels are arranged in adjacent, aligned positions with the elongatededge of the first concrete slab disposed in opposing spaced relationshiprelative to the elongated edge of the second concrete slab to therebypresent an elongated gap between the edges. In addition, an outboardsegment of the edge flap portion of the plastic sheet of the first panelis arranged in overlapping relationship relative to an outboard segmentof the edge flap portion of the plastic sheet of the second panel atsaid gap. The overlapping outboard segments are then welded together insitu with an upwardly extending seam.

In yet another aspect of the invention, a method is provided forconstructing a plastic lined concrete tank. In accordance with thisaspect of the invention, the method includes forming a plurality ofplastic lined concrete panels. Each of the panels includes a concreteslab having opposed, laterally spaced, elongated edges and an innersurface, and a plastic sheet having a plurality of anchoring projectionsprotruding outwardly from a face thereof. The forming of the panels isconducted in such a way that the face of each plastic sheet is engagedagainst the surface of a corresponding concrete slab with the anchoringprojections embedded in the concrete of the corresponding slab. Theplastic sheets are arranged, configured and positioned such that arespective edge flap portion thereof projects outwardly beyond each edgeof the corresponding slab. Each of the edge flap portions has anoutboard segment. The formed panels are arranged in adjacent, alignedpositions around a periphery of a tank foundation with the innersurfaces of the slabs facing inwardly, with the elongated edges of theslabs extending upwardly, with the respective elongated edges of eachslab disposed in opposing spaced relationship relative to the elongatededges of adjacent slabs to thereby present elongated gaps therebetween,with the plastic sheets disposed within the periphery, and with theoutboard segments of the edge flap portions of each sheet overlappingthe outboard segments of the edge flap portions of the sheets ofadjacent panels at said gap. The overlapping outboard segments arewelded together in situ with an upwardly extending seam.

Desirably, although not necessarily, a wedge welder may be used forwelding the overlapping segments together. When a wedge welder is used,a main body portion of the welder may ideally be located on an oppositeside of the plastic sheets from the concrete slabs during the welding.Ideally, a second portion of the wedge welder may be positioned withinthe gap between the edges during said welding.

In preferred forms of the invention, the edges of the panels may becoextensive in length and the edge flap portions may project outwardlybeyond the edges along essentially the entire length thereof. In otherpreferred forms of the invention, the panels may initially be formedwith the edges thereof disposed to extend in an essentially horizontaldirection. That is to say, the panels may be formed on the ground andthereafter erected so that the edges extend in an essentially uprightdirection. When the panels are erect, the welding may ideally beaccomplished by causing a welder mechanism to move upwardly along theoverlapping segments of the edge flap portions of the plastic sheets. Infurther accordance with the concepts and principles of the invention,the gap between the edges of the panels may be filled with a groutingmaterial after the welding has been completed. In this latter regard, itis a very desirable feature of the invention for the plastic sheets tobe arranged and constructed such that anchoring projections are providedon the edge flap portions so that the same project into the gap.Accordingly, during the grouting operation, a firm bond may be createdbetween the anchoring projections and the grout to hold the plasticsheet firmly against the concrete at all locations including the gaps.

In further accordance with the concepts and principles of the invention,the same provides plastic lined structures and plastic lined tanks thathave been built employing the methodology of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary, partial, perspective, elevational view of atank which has been constructed from a series of side-by-side alignedpanels in accordance with the methodology provided by the presentinvention;

FIG. 2 is an enlarged, fragmentary, partial cross-sectional view takenessentially in a downward direction along the line 2-2 of FIG. 1 andwhich also schematically illustrates the positioning of a welder used inaccordance with the concepts and principles of the invention;

FIG. 3 is a perspective view illustrating the methodology used inconstructing the panels used to construct the tank of FIG. 1;

FIG. 4 is a fragmentary, partial, perspective view of a panel used toconstruct the tank of FIG. 1, and wherein certain parts have been brokenaway to illustrate the internal construction of the panel;

FIG. 5 is perspective view illustrating the manner in which the erectedpanels are supported during construction of a tank;

FIG. 6 is a side elevational view of a wedge welder of the sort used toweld overlapping sheets of plastic together; and

FIG. 7 is an elevational cross-sectional view illustrating analternative procedure for constructing plastic-lined concrete tanks inaccordance with the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As mentioned above, the present invention relates generally to the fieldof concrete structures of the sort which may often be used in theconstruction of ground level or elevated concrete liquid containingstorage tanks and the like, and to plastic lined concrete structures andthe methodology used in the fabrication of composite plastic linedconcrete structures whereby the plastic lining is securely affixed to aconcrete wall. In connection with the foregoing, and in furtheraccordance with the invention, the tanks may have no roof or a roof thatcomprises a dome made from concrete, aluminum, fabric, or a flat panelroof with or without column supports that bear at or beneath the floorof the tank.

In a particularly preferred mode of the invention, the same providesmethodology for constructing plastic lined concrete tanks; however, aswill be apparent to those of ordinary skill in the concrete constructionart, the invention more broadly relates to the construction of any sortof plastic lined concrete structures where it is desirable toprefabricate a plurality of lined concrete panels, cause the panels tobe arranged in an aligned, side-by-side relationship, and thereafterweld the separate linings on adjacent panels together in situ to therebypresent a continuous sealed barrier.

Broadly, and with particular reference to FIGS. 1 through 5 of thedrawings, the method for constructing plastic lined concrete structuresincludes forming a plurality of plastic lined concrete panels 10. Suchpanels may be constructed adjacent the site where a tank is to be builtor at a remote location and shipped to the site. Panels 10 are similarlyconstructed and each includes a concrete slab 12, which may be generallyrectangular in shape and which desirably has a pair of opposed,laterally spaced, elongated lateral edges 14, 16 and a surface 18 whichextends laterally between edges 14, 16. As can be seen from thedrawings, in a preferred form of the invention, the slabs 12 maydesirably be curved so that when a series of the same are placed in analigned, side-by-side relationship, together they may be arranged so asto present the outer periphery of a generally round concrete tank 20which may be used to contain liquids generally, including water and thelike.

Each of the panels 10 also includes a plastic sheet 22 having aplurality of anchoring projections 24 protruding outwardly from a face26 thereof, and the panels 10 are desirably formed in such a way thatthe face 26 of each plastic sheet 22 is engaged against the surface 18of the corresponding concrete slab 12 with the anchoring projections 24embedded within the concrete of the slab 12. The sheets 22 may be formedfrom any sort of thermoplastic material which is essentially inert tothe substances that it will come into contact with during operation andtough enough to withstand the physical rigors associated with theconstruction and/or use of the lined structure. Ideally, the sheets 22may be formed from high density polyethylene, linear low densitypolyethylene, polypropylene and/or PVC. Desirably the plastic sheets 22are wider than the concrete slabs 12, and each sheet 22 is arranged andpositioned on its corresponding slab 12 in such a way that an edge flapportion 28 thereof projects outwardly beyond the edge 14 of thecorresponding slab 12 and an edge flap portion 30 projects outwardlybeyond the opposite edge 16 of the corresponding slab 12.

The sheets 22 generally may have a thickness ranging from about 0.5 mm(0.020 inch) to about 7 mm (0.28 inch), and desirably the thickness maybe within the range of from about 1.5 to 4 mm. For heavy duty operationunder adverse and/or corrosive chemical conditions, it has been foundthat a high density polyethylene material having a thickness of about 3mm may be desirable. Conversely, for applications where the tank willcontain relatively pure water and be exposed to mild temperatureconditions, it may be desirable, for economical reasons, to use a linearlow density polyethylene having a thickness of 2 mm.

As can be seen from FIGS. 1 and 2, the panels 10 of a series 32 thereofare disposed in adjacent, aligned positions with the elongated edge 14of each concrete slab 12 arranged in opposing spaced relationshiprelative to the elongated edge 16 of an adjacent concrete slab 12 so asto thereby present an elongated gap 34 between the edge 14 of one slab12 and the edge 16 of the adjacent slab 12. Desirably, the panels 10 arearranged so that an outboard segment 36 of the edge flap portion 30 ofthe plastic sheet of one panel 10 is disposed in overlappingrelationship to an outboard segment 38 of the edge flap portion 28 ofthe plastic sheet 22 of the adjacent panel at the gap 34. In accordancewith the concepts and principles of the invention, the overlappingsegments 36, 38 are welded together in situ.

A preferred procedure for forming the panels 10 is illustrated in FIGS.3 and 4. FIG. 3 illustrates a form box 40 which can be used in thefabrication of a panel 10. Form box 40 includes a lower former 41 havingan upper form surface 42, the lateral cross-section of which can best beseen in FIG. 4. It is to be noted in this regard that surface 42 isconvex and upwardly curved at the same degree of curvature as the insidecircumference of a tank to be constructed from the panels 10 formed inbox 40. A sheet 22 is then laid out on the surface 42 so that face 26faces upwardly and projections 24 protrude upwardly. It is to be notedin this latter regard that the projections 24 as illustrated arepreferably in the form of a multiplicity of elongated, generallyparallel T-shaped ribs 44 which are integral with the sheet 22. However,as will be apparent to those skilled in the field of plastic linings forconcrete panels, there are a variety of known shapes and forms for suchanchoring projections which have previously been in conventional use.

The sheet 22 is laid out such that the edge flap portions 28 and 30extend laterally beyond the lateral extremities of the upper formsurface 42 on each side thereof. In this regard, edge flap portion 30can be seen in FIG. 3; however, edge flap portion 28 on the oppositeside of sheet 22 is hidden from view. It is to be noted that in FIG. 3,the ribs 44 on edge flap portion 28 are shown schematically as singlelines. After sheet 22 has been appropriately positioned relative toupper form surface 42, reinforcing steel 46 is arranged atop sheet 22and side boards 48 are installed in locations for appropriately definingthe edges 14, 16 of the slab 12. In this latter regard, in the preferredform of the invention illustrated in the drawings and described herein,the side boards 48 and the edges 14, 16 defined thereby, desirablyextend in general parallelism with ribs 44. End boards 50 complete theinternal periphery of form box 40 which is intended to retain wetcementitious material after it is poured and while it is setting up intoa solid form. A quantity of wet cementitious material is then pouredonto the face 26 of sheet 22, appropriately shaped with a curved screedboard 51, and then allowed to harden to thereby form slab 12. After theslab 12 is formed, it is clear that the surface 18 thereof is engagedagainst the face 26 of sheet 22, and that the T-shaped ribs 44 areembedded within the concrete.

As can be appreciated from FIGS. 3 and 4 of the drawings, in oneparticularly preferred form of the invention, at the time the panels 10are formed, the edges 14, 16 of the slab 12 extend horizontally. That isto say, the panel 10 is lying in a generally horizontal position.Accordingly, in order to use the panels 10 to form a concrete tank, thesame must be erected so that the edges 14, 16 extend in an upwarddirection. Such erection may be accomplished in a conventional mannerusing a crane or a hoist or the like. After erection and prior to thecompletion of the entire tank, the individual panels 10 may be held inplace by respective sets of conventional braces 52 such as thoseillustrated in FIG. 5. Conventional weld plates (not shown) may also beused to further support the panels 10 during welding of the overlappingsegments 36, 38. Desirably, the panels 10 may be erected on a concretebase or foundation 33, or the like which may be lined or unlined.

As is illustrated in FIG. 1, a plurality of the pre-fabricated panels 10may be arranged so as to present a tank 20, the interior surfaces ofwhich will be lined with a plastic lining upon completion of theconstruction of the tank. Thus, a plurality of the panels 10 may bearranged in an aligned, side-by-side relationship as shown, with theelongated edges 14, 16 of adjacent panels 10, which are essentiallycoextensive in length, disposed in an opposing, spaced apartrelationship so as to present the upwardly extending gap 34therebetween. As mentioned above, adjacent panels 10 are positioned andarranged so that an outboard segment 36 of the edge flap portion 30 ofthe plastic sheet 22 of one panel 10 is disposed in overlappingrelationship to an outboard segment 38 of the edge flap portion 28 ofthe plastic sheet 22 of the adjacent panel 10 at the gap 34. Thisrelationship can best be seen from FIG. 2, where it can also be seenthat at least one of the ribs 44 may be removed from the outboardsegment 36 of edge flap portion 30 so as to avoid interference with thewelding operation. It should also be noted in connection with theforegoing that the ribs 44 on the edge flap portion 28 remain intact soas to provide a secure connection between the grouting material 70 andthe sheet 22 when the gap 34 is grouted as described hereinafter. Infurther connection with the foregoing, it should be noted also from FIG.1 that the edge flap portions 28, 30, which project outwardly beyond theelongated edges 14, 16, are desirably coextensive in vertical lengthwith one another as well as with the elongated edges 14, 16.

As described above, the panels 10 are pre-fabricated and arranged inplace after the concrete has become set. Alternatively, in accordancewith another embodiment of the invention, the panels 10 may be formed insitu in an already erect condition. In accordance with this aspect ofthe invention, and with specific reference to FIG. 7, an upstanding formassembly 140 may be employed to construct each panel 10. Form assembly140 may be erected on the base pad 33, and the same includes an innerform element 142 and an outer form element 144. These form elements 142,144 may be made from plywood or other prefabricated form system materialand may be appropriately curved to simulate the curvature of thecompleted concrete structure. As built, the elements 142, 144 aredisposed in a horizontally spaced, facing relationship so as to presenta concrete fillable space 145 therebetween. To construct each panel 10in situ, a plastic sheet 22 is placed over the interior face 146 of formelement 142 with the ribs 44 thereof (not shown in FIG. 7) projectinginto the space 145. Reinforcing steel (not shown in FIG. 7) may then bearranged in space 145 and fluid concrete may be poured into the space145. Upon drying, the concrete poured into space 145 presents slab 12.Thereafter, the form assembly 140 is removed to present an already inplace panel 10. As will be appreciated by those skilled in the art, aseries of laterally spaced and aligned panels 10 may be constructed inthis manner around the periphery of the tank. These panels will bespaced apart laterally as described above so as to present a gap 34between adjacent aligned panels 10. In addition, the plastic sheetsextend laterally outwardly beyond the lateral edges of the panels asdescribed above so as to present corresponding outboard segment 36, 38which may then be welded together in accordance with the concepts andprinciples of the invention.

In another embodiment of the invention, the panels 10 may be formedusing concrete spraying methodology. In accordance with this form of theinvention, a form assembly similar to the assembly 140 may be used.However, in this case, the outer form element 144 is not needed. Theconstruction of the panel 10 in this case simply involves constructingthe form element 144, placing the plastic sheet over the face 146 of thelatter with the ribs projecting outwardly, installing the steelreinforcing material, and spraying concrete onto the exposed surface ofplastic sheet 22.

In each of the embodiments described above, the final arrangement of thepanels 10 is as illustrated in FIGS. 1 and 2.

Preferably, each gap 34 may vary in width from about 4 inches to about20 inches, and desirably the width of the gap 34 should be about 6 to 8inches. Advantageously, each of the flap portions 28, 30 may projectlaterally and outwardly beyond edges 14, 16 of slab 12 for a distance offrom about 4 inches to about 20 inches, and ideally the outboardsegments 36, 38 should overlap a minimum of 2 inches and a maximum of 10inches. Generally, it is preferred for the overlapping segments 36, 38to be positioned centrally of the gap 34. In a particularly preferredform of the invention, the gap 34 may be about 7 inches wide and theflap portions 28, 30 may project outwardly beyond the edges 14, 16 ofslab 12 for a distance of about 5 inches, whereby the overlap is about 3inches wide.

The overlapping outboard segments 36 and 38 may be welded together insitu using hot air welding, hot gas welding, infrared element weldingand/or wedge welding. However, wedge welding may desirably be used inaccordance with the preferred aspects of the invention. A typical wedgewelder 56 is illustrated in FIG. 6 where it can be seen that the welder56 includes a main body portion 58 where the controls and drivemechanisms are located and a bottom sled portion 60. The overalloperational characteristics of wedge welders are conventional and wellknown, and such mechanisms are commonly used to weld overlapping,horizontally extending edge flap portions of adjacent plastic sheetstogether. Accordingly, as shown in FIG. 6, the wedge welder is employedto weld overlapping outboard segments 36 and 38 together using a heatedwedge 62 and pinch wheels 64, 66. As is well known, pinch wheel 64 maybe a driven wheel carried by main body portion 58 while pinch wheel 66carried by bottom sled portion 60 may be either a driven wheel or anidler wheel. Conventionally, during operation the wedge welder 56travels in the direction of the arrow 61 in FIG. 6.

In further accordance with the concepts and principles of the presentinvention, the overlapping outboard segments 36, 38 of the edge flapportions 28, 30 are welded together in situ using a wedge welder 56.This operation is best illustrated in FIG. 2 where it can be seen thatthe main body portion 58 of the welder 56 is desirably positioned on theopposite sides of the plastic sheets 22 from the concrete slabs 12,whereas the bottom sled portion 60 of the welder 56 is desirablypositioned within gap 34. The bottom sled portion 60 may desirably beprovided with slots 75 which cooperate with ribs 44 or other anchoringprojections on flap 28 for guiding the welder 56 along the gap 34.Ideally, the wedge welder 56 may be started at the bottom of eachoverlapping set of outboard segments 36, 38 and caused to move upwardlyalong the sheets 22 while the segments 36, 38 are welded together toproduce a continuous, upwardly extending seam 68, which desirably mayvary from 0.5 inch to 2 inches in width and ideally is about 1 inch inwidth. Alternatively, the welder 56 may be started at the top and causedto move downwardly along the edges of the sheets. In accordance with theparticularly preferred form of the invention described above where thegap 34 is 7 inches wide, the bottom sled portion 60 may ideally be about5-6 inches wide.

After each seam is completed, the gap 34 may desirably be filled with agrouting material 70 as illustrated schematically in FIG. 1. Asexplained above, it is desirable in connection with the invention foranchoring projections 24 to be arranged such that the same project intothe gap 34 where they may be surrounded by grout during the groutingprocess. This insures a rigid and secure connection between the plasticsheets 22 and the grout. After the gaps 34 are fully grouted, the tank20 may be prestressed/post-tensioned using wires or strands (not shown).

1. A method for constructing a plastic lined concrete structurecomprising: forming first and second plastic lined concrete panels, eachpanel including a concrete slab having an elongated edge and a surface,and a plastic sheet having a plurality of anchoring projectionsprotruding outwardly from a face thereof, said forming being conductedin such a way that said face of each plastic sheet is engaged againstthe surface of a corresponding concrete slab and said anchoringprojections are embedded in the concrete of the corresponding slab, saidplastic sheets each being arranged and positioned such that an edge flapportion thereof projects outwardly beyond the edge of the correspondingslab; causing said panels to be arranged in adjacent, aligned positionswith the elongated edge of the concrete slab of the first panel disposedin opposing spaced relationship relative to the elongated edge of theconcrete slab of the second panel to thereby present an elongated gapbetween the edges, and with an outboard segment of the edge flap portionof the plastic sheet of the first panel overlapping an outboard segmentof the edge flap portion of the plastic sheet of the second panel atsaid gap; and welding said overlapping segments together.
 2. A method asset forth in claim 1, wherein a wedge welder is used for welding saidoverlapping segments together.
 3. A method as set forth in claim 2,wherein a main body portion of said welder is located on an oppositeside of the plastic sheets from the concrete slabs during said welding.4. A method as set forth in claim 1, wherein said edges are coextensivein length and said edge flap portions project outwardly beyond the edgesalong essentially the entire length thereof.
 5. A method as set forth inclaim 1, wherein said panels are initially formed with said edgesthereof disposed to extend in an essentially horizontal direction, andsaid causing includes erecting said panels so that the edges extend inan essentially upright direction.
 6. A method as set forth in claim 3,wherein a second portion of said wedge welder is positioned within saidgap between said edges during said welding.
 7. A method as set forth inclaim 1 comprising filling said gap with a grouting material after saidwelding has been completed.
 8. A method as set forth in claim 2, whereinsaid panels are initially formed with said edges thereof disposed toextend in an essentially horizontal direction, and said causing includeserecting said panels so that the edges extend in an essentially uprightdirection.
 9. A method as set forth in claim 8, wherein said welding isaccomplished by causing said welder to move upwardly along saidoverlapping segments.
 10. A method for constructing a plastic linedconcrete structure comprising: providing first and second plasticsheets, each sheet having a face and a plurality of anchoringprojections protruding outwardly from said face; forming a first plasticlined concrete panel by causing a first quantity of wet cementitiousmaterial to come into contact with and cover a portion of said face ofthe first plastic sheet, permitting the first quantity of cementitiousmaterial to set in the form of a first solid concrete slab having theanchoring projections of the first plastic sheet embedded therein, saidconcrete slab having an elongated edge, and arranging said first plasticsheet and said first quantity of wet cementitious material relative toone another such that an edge flap portion of the first plastic sheetprojects outwardly beyond said edge of the first slab after thecementitious material has become set; forming a second plastic linedconcrete panel by causing a second quantity of wet cementitious materialto come into contact with and cover a portion of said face of the secondplastic sheet, permitting the second quantity of cementitious materialto set in the form of a second solid concrete slab having the anchoringprojections of the second plastic sheet embedded therein, said concreteslab having an elongated edge, and arranging said second plastic sheetand said second quantity of wet cementitious material relative to oneanother such that an edge flap portion of the second plastic sheetprojects outwardly beyond said edge of the second slab after thecementitious material has become set; causing said panels to be arrangedin adjacent, aligned positions with the elongated edge of the firstconcrete slab disposed in opposing spaced relationship relative to theelongated edge of the second concrete slab to thereby present anelongated gap between the edges, and with an outboard segment of theedge flap portion of the plastic sheet of the first panel overlapping anoutboard segment of the edge flap portion of the plastic sheet of thesecond panel at said gap; and welding said overlapping outboard segmentstogether.
 11. A method as set forth in claim 10, wherein a wedge welderis used for welding said overlapping segments together.
 12. A method asset forth in claim 11, wherein a main body portion of said welder islocated on an opposite side of the plastic sheets from the concreteslabs during said welding.
 13. A method as set forth in claim 10,wherein said edges are coextensive in length and said edge flap portionsproject outwardly beyond the edges along essentially the entire lengththereof.
 14. A method as set forth in claim 10, wherein said panels areinitially formed with said edges thereof disposed to extend in anessentially horizontal direction, and said causing includes erectingsaid panels so that the edges extend in an essentially uprightdirection.
 15. A method as set forth in claim 12, wherein a secondportion of said wedge welder is positioned within said gap between saidedges during said welding.
 16. A method as set forth in claim 10comprising filling said gap with a grouting material after said weldinghas been completed.
 17. A method as set forth in claim 11, wherein saidpanels are initially formed with said edges thereof disposed to extendin an essentially horizontal direction, and said causing includeserecting said panels so that the edges extend in an essentially uprightdirection.
 18. A method as set forth in claim 17, wherein said weldingis accomplished by causing said welder to move upwardly along saidoverlapping segments.
 19. A method for constructing a plastic linedconcrete tank comprising: forming a plurality of plastic lined concretepanels, each panel including a concrete slab having opposed, laterallyspaced, elongated edges and an inner surface, and a plastic sheet havinga plurality of anchoring projections protruding outwardly from a facethereof, said forming being conducted in such a way that said face ofeach plastic sheet is engaged against the surface of a correspondingconcrete slab with said anchoring projections embedded in the concreteof said corresponding slab, said plastic sheets each being arranged,configured and positioned such that a respective edge flap portionthereof projects outwardly beyond each edge of the corresponding slab,each said edge flap portion having an outboard segment; causing saidpanels to be arranged in adjacent, aligned positions around a peripheryof a tank foundation with the inner surfaces of the slabs facinginwardly, with the elongated edges of the slabs extending upwardly, withthe respective elongated edges of each slab disposed in opposing spacedrelationship relative to the elongated edges of adjacent slabs tothereby present elongated gaps therebetween, with the plastic sheetsdisposed within said periphery, and with the outboard segments of theedge flap portions of each sheet overlapping the outboard segments ofthe edge flap portions of the sheets of adjacent panels at said gap; andwelding said overlapping outboard segments together.
 20. A method as setforth in claim 19, wherein a wedge welder is used for welding saidoverlapping segments together.
 21. A method as set forth in claim 20,wherein a main body portion of said welder is located on an oppositeside of the plastic sheets from the concrete slabs during said welding.22. A method as set forth in claim 19, wherein said panels are initiallyformed with said elongated edges extending in a generally horizontaldirection and said causing includes erecting the panels so that saidelongated edges extend in an upright direction.
 23. A method as setforth in claim 19, wherein said placing includes positioning saidelongated edges in a generally parallel relationship on opposite sidesof said gap.
 24. A method as set forth in claim 19, wherein said formingincludes applying a respective quantity of a wet cementitious materialto a portion of the face of each of said sheets, and thereafter allowingthe respective quantities of cementitious material to set with saidanchoring projections submerged therein.
 25. A method as set forth inclaim 19 comprising filling said gaps with a grouting material aftersaid welding has been completed.
 26. A method as set forth in claim 21,wherein a second portion of said wedge welder is positioned within saidgap between said edges during said welding.
 27. A method as set forth inclaim 20, wherein said panels are initially formed with said elongatededges extending in a generally horizontal direction and said causingincludes erecting the panels so that said elongated edges extend in anupright direction.
 28. A method as set forth in claim 27, wherein saidwelding is accomplished by causing said welder to move upwardly alongsaid overlapping segments.
 29. A method as set forth in claim 6, whereinsaid panels are initially formed with said edges thereof disposed toextend in an essentially horizontal direction, and said causing includeserecting said panels so that the edges extend in an essentially uprightdirection.
 30. A method as set forth in claim 29, wherein said weldingis accomplished by causing said welder to move upwardly along saidoverlapping segments.
 31. A method as set forth in claim 15, whereinsaid panels are initially formed with said edges thereof disposed toextend in an essentially horizontal direction, and said causing includeserecting said panels so that the edges extend in an essentially uprightdirection.
 32. A method as set forth in claim 31, wherein said weldingis accomplished by causing said welder to move upwardly along saidoverlapping segments.
 33. A method as set forth in claim 26, whereinsaid panels are initially formed with said elongated edges extending ina generally horizontal direction and said causing includes erecting thepanels so that said elongated edges extend in an upright direction. 34.A method as set forth in claim 33, wherein said welding is accomplishedby causing said welder to move upwardly along said overlapping segments.35. A plastic lined concrete structure built using the method ofclaim
 1. 36. A plastic lined concrete structure built using the methodof claim
 30. 37. A plastic lined concrete structure built using themethod of claim
 10. 38. A plastic lined concrete structure built usingthe method of claim
 32. 39. A plastic lined concrete tank built usingthe method of claim
 19. 40. A plastic lined concrete tank built usingthe method of claim
 34. 41. A method as set forth in claim 1, whereinthe edge flap portion of the plastic sheet of the second panel has atleast one anchoring projection which projects into said gap after theoverlapping segments have been welded together.
 42. A method as setforth in claim 41 comprising filling said gap with a grouting materialafter said welding has been completed.
 43. A method as set forth inclaim 10, wherein the edge flap portion of the plastic sheet of thesecond panel has at least one anchoring projection which projects intosaid gap after the overlapping segments have been welded together.
 44. Amethod as set forth in claim 43 comprising filling said gap with agrouting material after said welding has been completed.
 45. A method asset forth in claim 19, wherein the edge flap portions of the plasticsheets of said adjacent panels each has at least one anchoringprojection which projects into said gap after the overlapping segmentshave been welded together.
 46. A method as set forth in claim 45comprising filling said gap with a grouting material after said weldinghas been completed.
 47. A method as set forth in claim 1, wherein saidplastic sheets have a thickness ranging from about 0.05 mm to about 7mm.
 48. A method as set forth in claim 1, where in said sheets areformed from either a high density polyethylene or a linear low densitypolyethylene.
 49. A method as set forth in claim 47, where in saidsheets are formed from either a high density polyethylene or a linearlow density polyethylene.
 50. A method as set forth in claim 1, whereinthe anchoring projections are in the form of elongated, T-shaped ribs.51. A method as set forth in claim 10, wherein said plastic sheets havea thickness ranging from about 0.05 mm to about 7 mm.
 52. A method asset forth in claim 10, where in said sheets are formed from either ahigh density polyethylene or a linear low density polyethylene.
 53. Amethod as set forth in claim 51, where in said sheets are formed fromeither a high density polyethylene or a linear low density polyethylene.54. A method as set forth in claim 10, wherein the anchoring projectionsare in the form of elongated, T-shaped ribs.
 55. A method as set forthin claim 19, wherein said plastic sheets have a thickness ranging fromabout 0.05 mm to about 7 mm.
 56. A method as set forth in claim 19,where in said sheets are formed from either a high density polyethyleneor a linear low density polyethylene.
 57. A method as set forth in claim55, where in said sheets are formed from either a high densitypolyethylene or a linear low density polyethylene.
 58. A method as setforth in claim 19, wherein the anchoring projections are in the form ofelongated, T-shaped ribs.
 59. A method as set forth in claim 1, whereinsaid causing includes forming said panels in situ.
 60. A method as setforth in claim 10, wherein said causing includes forming said panels insitu.
 61. A method as set forth in claim 19, wherein said causingincludes forming said panels in situ.
 62. A method as set forth in claim8, wherein said welding is accomplished by causing said welder to moveupwardly along said overlapping segments.
 63. A method as set forth inclaim 17, wherein said welding is accomplished by causing said welder tomove upwardly along said overlapping segments.
 64. A method as set forthin claim 29, wherein said welding is accomplished by causing said welderto move upwardly along said overlapping segments.